Customer service phone lines routinely tell consumers their “call is being recorded for quality assurance purposes.” But a new Walmart patent shows the retailer might someday collect checkout line sounds and capture conversations between customers and the cashier ringing up their milk and diapers.

The patent, which was reported by BuzzFeed Wednesday, would use a system of sound sensors to listen in on workers' activities and interactions, gathering audio data such as the beeps and rustling of bags to determine the number of items in a transaction, the patent says, or conversations between cashiers and customers to hear whether, say, workers were greeting customers.

“A need exists for ways to capture the sounds resulting from people in the shopping facility and determine performance of employees based on those sounds,” the retail behemoth wrote in its patent application, called “Listening to the Frontend.”

The technology may never be built or implemented – it is only a patent – but provides yet another example of the ways employers are using technology to more closely monitor employee behavior and collect vast amounts of data to manage them.

Earlier this year, Amazon won patents for a wristband that would verify whether warehouse workers are correctly processing items, setting off vibrations to guide workers' hands to the right bin, reported GeekWire. UPS uses sensors to track things like whether seat belts are being worn and the opening and closing of doors on its delivery trucks, according to ABC News.

Technology even exists that allows companies to track workplace keyboards to see how fast employees are typing, said Brian Kropp, group vice president of Gartner’s human resources practice, as well as place sensors in workers' chairs to track how much they’re not sitting at their desks.

“But is that because they’re going and talking and collaborating with their colleagues or because they’re going out to take a smoke break?” Kropp said. While the tools for collecting more and more data are increasingly available, he said, for the most part, “the models to turn that data into knowledge are not there.”

In a statement, Walmart said it files patents often “but that doesn’t mean the patents will actually be implemented. We’re always thinking about new concepts and ways that will help us further enhance how we serve customers. This patent is a concept that would help us gather metrics and improve the checkout process by listening to sounds produced by the bags, carts and cash registers and not intended for any other use.”

Walmart spokesman Ragan Dickens said that while customers' or associates' voices could be picked up if sounds were recorded, the intent is not to gather or analyze those conversations. Yet in the patent, Walmart says "the system can process the audio of the conversation to determine whether the employee stationed at the terminal is greeting guests.”

Walmart indicated the concept was designed as a possible efficiency hack that could help decrease store costs and boost guest satisfaction, writing that “one way to track performance metrics for employees is the use of a system including sound sensors near point of sale (‘POS’) terminals." The system could “correlate the audio data with an employee that is stationed at the terminal, and determine a performance metric for the employee.”

The patent’s focus on data-driven efficiency fits with “the next frontier” for retailers, said Neil Stern, senior partner at the retail consultancy McMillanDoolittle, in an email.

“The prior era of retail was focused on growth – retailers could remain inefficient in the way they ran their businesses as long as they could open new stores and drive comp store sales, the two measures they were essentially rated on," he said.

But “the future will now be about how efficiently the box can be run,” Stern said. While the patent may seem invasive, Stern believes retail employees, many of whom are already under security video surveillance, might tune out the monitoring relatively quickly, even if it leads to a greater discussion about privacy and employee rights.

“When does it cross the line between data efficiency and an outright invasion of privacy?” he said.

Paula Brantner, a senior adviser for Workplace Fairness, a nonprofit organization providing legal information to workers about their rights, said if Walmart were to use the patent someday, she hoped they would communicate, as call centers do, that employees and customers are being monitored, as well as “that this is how the monitoring would be used and that they would not use it in a punitive way, but to make employees' lives easier."

If neither customers nor employees were informed, she questioned whether it could run afoul of state-by-state regulations on how many parties in a recorded conversation must be notified.

“If I’m suddenly being recorded, and I’m standing in line chatting with my boyfriend and the audio could pick that up, I’d want to know about that,” she said. (Walmart’s Dickens said if the concept was ever implemented, employees and customers would be notified and the company would comply with all applicable laws.)

While Walmart’s patent may never see actual use, Kropp said companies are quickly adopting “nontraditional” approaches to collecting data as more technology becomes available. In 2015, just 5 percent of companies his firm surveyed said they were tracking data like employee movements, the location of work computers, the text in internal instant messaging tools or data about “workspace usage,” the category where he’d place Walmart’s patent.

But by early this year, 40 percent of the 239 companies Gartner surveyed said they were at least experimenting with one of those or other nontraditional techniques. He said retailers that have long relied on customer feedback tools like surveys are increasingly looking for “more real-time – and ideally more reliable – measures of customer experience, rather than just asking the customer for feedback.”

Jena McGregorJena McGregor writes on leadership issues in the headlines – corporate management and governance, workplace trends and the personalities who run Washington and business. Prior to writing for the Washington Post, she was an associate editor for BusinessWeek and Fast Company magazines and began her journalism career as a reporter at Smart Money. Follow